Description:
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output before header() should give error, but no warning is shown and the header is actually sent (HTTP 403, in this case)

*NOTE* I am testing this with PHP 7.0.1 via XAMPP

Test script:
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<?php
echo 'Some string';
header('HTTP/1.1 403 Forbidden');


Expected result:
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PHP Warning:  Cannot modify header information - headers already sent by (output started at Z:\test\file.php:2) in Z:\test\file.php on line 3


Actual result:
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HTTP 1.1 403 Forbidden
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Some string